Plastic-eating Caterpillar Could Solve Global Plastic Pollution.

A Spanish biologist and amateur beekeeper, Federica Bertocchini, has discovered a plastic-eating caterpillar that could be the solution to global plastic pollution. The caterpillar’s ability to consume plastic was accidentally discovered during routine bee hive maintenance and it’s has since been studied by Bertocchini and her peers at the University of Cambridge. Their findings have been published in Current Biology in April 2017.

Federica Bertocchini, of the Institute of Biomedicine and Biotechnology of Cantabria, made her discovery when removing wax worms from the honeycombs of a beehive. Placing them briefly on a plastic bag, Bertocchini noticed the caterpillars created holes in the bag. She contacted her peers at the University of Cambridge, Paolo Bombelli and Christopher J. Howe, to study this potentially significant discovery.

The Current Biology paper confirms the findings of the group, who conducted a controlled experiment with one hundred wax worms. They discovered it took forty minutes for the worms to create holes in a plastic bag; with each worm producing on average one to three holes per hour. The bag mass was reduced by 40 micrograms in that time. Other researchers have previously discovered bacteria that can break down plastic, but only by 0.13 micrograms per day.

Image courtesy of Nick Curzon

Chemical bonds in plastic are usually resistant to biodegradation but the researchers believe the wax worms may be able to breakdown this plastic, or polyethylene, because their natural diet is beeswax. The Honeycomb moths lay their eggs inside beehives and their young, wax worms, eat beeswax. Beeswax contains some of the same hydrocarbon compounds as found in plastic bags.

Howe confirmed it was important to determine if the wax worms possess a certain enzyme that digests the plastic or if they are just chewing the material into smaller pieces. Their tests showed it is a chemical or combination of chemicals within the worms that are causing the plastic to be converted into a colourless and odourless liquid, ethylene glycol, that is used industrially in the manufacture of antifreeze and polyester fabrics. Whilst this liquid is slightly toxic to humans, it is less harmful to the planet than the current scale of plastic pollution.

It is not yet known if the chemical is produced by the wax worms or by bacteria in their guts and it is thought to be an enzyme. A Chinese study in 2014 discovered the caterpillars of the Indian meal moth, which also lives in beehives, could digest polyethylene due to two species of gut bacteria.

The next step is to narrow down and identify the chemical breaking the plastic’s bonds. If it can be isolated and is an enzyme, the gene that controls it may be obtained and inserted into bacteria to degrade plastics. Whilst wax worms are already cultivated for fishing bait, bacteria would be easier to cultivate on a large scale to tackle global plastic pollution.

About eighty million tonnes of plastic are produced globally each year, with five-hundred billion single-use plastic bags used per year. These plastics do not naturally biodegrade. Instead, they are degraded by sunlight into tiny plastic or ‘microplastics’ that pollute the ocean and eventually enter the human food chain. Plastic bags are consumed by marine life such as sea turtles and sperm whales who mistake floating bags for jellyfish and squid. Twenty-nine sperm whales stranded on shores around the North Sea in January 2016 had stomachs filled with plastic debris and likely died from starvation due to stomachs full of plastic and from gut blockages.

Whilst this discovery of a plastic-eating caterpillar could be crucial to solving the global plastic problem, Howe has cautioned it could be several years until cultivating the bacteria is possible. Bertocchini has urged people to continue acting to reduce plastic disposal in the first place.

“We are planning to implement this finding into a viable way to get rid of plastic waste, working towards a solution to save our oceans, rivers, and all the environment from the unavoidable consequences of plastic accumulation,” she said.

“However, we should not feel justified to dump polyethylene deliberately in our environment just because we now know how to biodegrade it.”

About Author

Kathryn has lived in the UK, Egypt, South Africa and New Zealand and is a trained scuba diving instructor and Great White shark safari guide. She is the author of No Damage (December 2014), the Managing Editor of The Scuba News New Zealand, a freelance writer, public speaker and co-founder of the marine conservation cause Friends for Sharks (August 2014). In 2015 she organised and completed a 10-month global speaking tour in aid of shark conservation: 87 events, 8 countries, 7000 people.
Learn more about Kathryn’s book, No Damage at:
http://www.kathrynhodgsonauthor.com/books/no-damage/